1. Field of the Invention
The present invention relates to writing instruments, and more particularly to ball-point pens having an actuator mechanism which, under the application of pressure against a return spring, moves the writing cartridge from is writing position to its retracted position, and vice versa.
2. Description of the Prior Art
Most known ball-point pens and other writing instruments of the above-mentioned actuator type feature as part of their actuating mechanism an actuator button which protrudes from the upper end of the pen or writing instrument, both in the writing position and in the retracted position of the cartridge, albeit to a different length in the case of certain actuating mechanisms. The resulting configuration of the upper portion of the writing instrument is a protruding button surrounded by a larger shoulder. This shoulder configuration is even more pronounced in the case of multi-cartridge writing instruments, where the actuating mechanism requires a longer actuating stroke, and where the actuator pin consequently protrudes further from the main body of the pen and is therefore also more susceptible to accidental damage.
Other prior art ball-point pens and writing instruments use actuating mechanisms in which the actuator pin is replaced by an actuator cap which reaches a distance over the main shell of the pen, to near the mid-portion of the latter. Here, too, the lower end of the actuator cap forms an annular shoulder around the pen body. This shoulder is particularly undesirable, because it is located in that portion of the writing instrument which constitutes the grip zone. It has therefore become necessary, in all cases where an actuator cap is used, to fabricate the latter from metal, so as to minimize the wall thickness and the resultant height of the annular shoulder on the lower end of the actuator cap.
A still further disadvantage flowing from the annular shoulder on the lower end of the actuator cap relates to the difficulty of automatically feeding this type of writing instrument to writing machines. There, both the upwardly protruding actuator pin and the annular shoulder in the mid-portion of the writing instrument are undesirable and represent difficulties in the automatic handling of the pens.
Lastly, ball-point pens and writing instruments are subject to certain expectations by the user in regard to their aesthetic appearance, especially their overall shape and elegance of outline, which should not be dictated by the component parts of the actuator mechanism.